1. Field of the Invention
Exemplary embodiments of the present invention relate to a light emitting diode
(LED) package and, more particularly, to an LED package which includes a housing configured to surround uplift portions formed on lead frames electrically connected to an LED chip. The LED package is to increase a heat dissipation area while increasing physical strength between the lead frames and preventing moisture absorption.
2. Discussion of the Background
A light emitting diode (LED) is a semiconductor device that emits light through recombination of holes and electrons in a P-N junction between a P-type semiconductor and an N-type semiconductor. Such an LED may be manufactured as a package structure having an LED chip mounted therein.
A conventional LED package 1 includes first and second lead frames 11, 12 having a direct type heat dissipation structure. As shown in FIG. 1(a), one of the first and second lead frames 11, 12 separated from each other, for example the first lead frame 11, is formed with a hole-cup 111 by half-etching.
A housing 13 is formed to support the first and second lead frames 11, 12, and an LED chip 14 is mounted on the bottom of the hole-cup 111. As shown in FIG. 1(b), the housing 13 includes the hole-cup 111 and a cavity 131 which exposes portions of the first and second lead frames 11, 12. The housing 13 may be formed by, for example, polyphthalamide (PPA) injection or epoxy molding.
The LED chip 14 mounted in the hole-cup 111 is electrically connected to the second lead frame 12 via a bonding wire W. The hole-cup 111 is filled with a light-transmitting resin 16 containing at least one phosphor, and color uniformity of light emitted from the LED chip 14 can be enhanced by the phosphor in the hole-cup 111. An encapsulation material (not shown) may be disposed in the cavity 131 of the housing 13 to protect the LED chip 14 mounted in the hole-cup 111.
When electric power is applied to the lead frames 11, 12 of the LED package 1 from an external power source, the LED chip 14 is driven to emit light to the outside through the encapsulation material. Here, on a lower surface of the LED package shown in FIG. 1(c), the first lead frame 11 having the LED chip 14 mounted thereon and the second lead frame 12 are exposed outside, and may thereby enhance heat dissipation efficiency from the LED chip 14.
However, although the LED package 1 shown in FIG. 1 may have high heat dissipation efficiency, a portion dividing the first and second lead frames 11, 12 may have low physical strength and may be vulnerable to moisture, and the hole-cup 111 formed by half-etching may be non-uniform, thereby making it difficult to maintain uniformity of light generated from the LED chip 14. Further, when the hole-cup 111 is formed by etching, manufacturing costs of the package may increase, thereby limiting mass production.
A conventional LED package 2 developed to solve the problems of such a conventional LED package 1 having low physical strength and vulnerability to moisture includes first and second lead frames 21, 22 as shown in FIG. 2(a). Specifically, the first lead frame 21 includes a first horizontal section 21a, a protrusion 21b bent from the horizontal section 21a and protruding to a predetermined distance from the first horizontal section 21a, and a second horizontal section 21c bent and extending from the protrusion 21b. Further, the second lead frame 22 includes a third horizontal section 22afacing the first horizontal section 21a,a depression 22b bent from the third horizontal section 22a and depressed into the second lead frame 22, and a fourth horizontal section 22c bent from the depression 22b and facing the second horizontal section 21c. The protrusion 21b of the first lead frame 21 is disposed inside the depression 22b of the second lead frame 22.
Referring to FIG. 2(b), the LED package 2 has a housing 23 configured to support the first and second lead frames 21, 22 and having a cavity 231 exposing an LED chip 24. A bonding wire W and portions of the first and second lead frames 21, 22 are exposed through the cavity 231. The cavity 231 may be provided with an encapsulation material (not shown) to encapsulate the LED chip 24.
The first lead frame 21 includes a down-set portion 211 formed by stamping, and the LED chip 24 is mounted in the down-set portion 211. The down-set portion 211 is filled with a light-transmitting resin containing at least one phosphor. As shown in FIG. 2(c), a lower surface of the down-set portion 211 is coplanar with a lower surface of the LED package 2. In FIG. 2, the LED package 2 may have low heat dissipation efficiency from the LED chip 24 due to a narrow heat dissipation area, which corresponds to the lower surface of the down-set portion 211.